Chemical and Structural Studies of Antibodies and Histocompatibility Antigens. It is the purpose of this project to study the chemistry and structure of antibodies and histocompatibility antigens. Antibodies of different specificities and allotype are purified. The chemical sequence of both the light and heavy chains is obtained in order to gain some insight into the nature of antibody specificity and the generation of diversity. Improvements in the isolation methods of histocompatibility antigens and tumor antigens are currently being pursued. The characterization of the chemical structure of these proteins is being approached by micro methods and the relationship of the amino acid sequence to immunoglobulin structure or other known structures is being analyzed. Epoxide hydrase plays a critical role in chemical-induced mutagenesis and carcinogenesis. Chemical modification studies have been undertaken with the goal of identifying aminoacid residues which are essential for catalytic function. BIBLIOGRAPHIC REFERENCES: Appella, E., Tanigaki, N., Henriksen, O., Pressman, D., Smith, D. F. and Fairwell, T.: Comparative chemical analysis and partial amino acid sequence of the heavy chains of HL-A antigens. Cold Spring Harbor Symp. Quant. Biol. 41: 341-342, 1977. Lee, Y., Roholt, O. A., Appella, E. and Pressman, D.: Position of a light chain tyrosyl residue in the combining site of a rabbit anti-rho-azobenzoate antibody. Immunochemistry 14: 269-276, 1977.